Planting the 2021 wheat crop

Much of wheat’s yield potential is determined at planting. To attain top yields, timely planting coupled with appropriate seeding practices can be critical for ensuring an even and uniform stand.

winter wheat
Photo by Dennis Pennington, MSU

Planting preparations

Achieving top yields requires a uniform stand of healthy seedlings. This is dependent on seeds being dropped as evenly as possible and at a uniform depth. Good seed placement, in turn, requires that fields are appropriately prepped, and planting equipment receive disciplined inspection, necessary adjustments and deliberate calibrations.

Tillage systems

Wheat establishment can be successful under conventional, minimum tillage and no-till systems. Generally speaking, no-till has won favor in recent years. It tends to result in more unevenness in the stand, but it can often provide improved moisture retention and less susceptibility to cold temperature damage. Tillage, even at a minimal level, can be helpful in distributing and incorporating residue, fertilizer and lime; and create a more uniform seedbed. Tillage can also be useful when attempting to reduce disease inoculum borne in crop residue (e.g. corn stubble or stalks infected with Fusarium).

Seeding date

Ideally, winter wheat is planted while the soil and air temperatures are still warm to ensure that seedlings can emerge quickly and in plenty of time to develop a couple of tillers and a strong root system. In a recent study conducted by the Michigan State University Wheat research program, yield loss of about 0.6 bushels per day occurs when planting after Oct. 1.

While the Hessian fly no longer poses a significant threat to wheat in Michigan, the fly-free-date is still a useful reference (Table 1). The standard fly-free-date is during the first week of September in the northern Lower Peninsula, around mid-September in mid-state areas and approximately the third or fourth week of September for southern Michigan. Highest yields are often attained when seedlings emerge within two weeks following the posted fly-free-date, assuming heat unit accumulation is near normal in October and November. When wheat is planted within a few days of the fly-free-date, seeding rates and fall-applied nitrogen rates should be significantly reduced to avoid excessive growth. The goal is to plant early enough to achieve two to three tillers produced prior to the winter vernalization period.

Table 1. Hessian fly-free-dates for Michigan

County

Sept.

County

Sept.

County

Sept.

County

Sept.

Alcona

6

Eaton

16

Lapeer

15

Ogemaw

10

Allegan

20

Emmett

4

Leelanau

8

Osceola

10

Alpena

9

Genesee

17

Lenawee

25

Oscoda

7

Antrim

4

Gladwin

12

Livingston

16

Otsego

6

Arenac

13

Grand Traverse

8

Macomb

18

Ottawa

19

Barry

18

Gratiot

15

Manistee

13

Presque Isle

8

Bay

14

Hillsdale

19

Mason

13

Roscommon

7

Benzie

16

Huron

13

Mecosta

12

Saginaw

16

Berrien

23

Ingham

17

Midland

15

Sanilac

15

Branch

19

Ionia

16

Missaukee

9

St. Clair

16

Calhoun

19

Iosco

7

Monroe

21

St. Joseph

23

Cass

22

Isabella

11

Montcalm

15

Shiawassee

16

Charlevoix

3

Jackson

16

Montmorency

7

Tuscola

15

Cheboygan

4

Kalamazoo

20

Muskegon

18

Van Buren

22

Clare

12

Kalkaska

5

Newaygo

15

Washtenaw

18

Clinton

17

Kent

18

Oakland

16

Wayne

18

Crawford

6

Lake

13

Oceana

16

Wexford

Oftentimes, weather conditions make it difficult to plant wheat on time. How late a wheat crop can be planted is really a question of how much risk a grower is willing to take. If a grower expects to have the crop insured, then the answer is straightforward because Oct. 25 is the last planting date for crop insurance eligibility. For those trying to estimate the odds of achieving a reasonable yield, it is important to recognize that the challenge to late wheat is not only the inherent constraints on grain yield, but also its greater susceptibility to winter injury.

Planting wheat on time starts with the previous crop. Soybean fields that are to be planted to wheat in the fall can benefit from management considerations such as optimum planting time and maturity group (MG) selection (Figure 1). Selection of late-maturity soybean varieties (e.g., 3.0 versus 2.0 MG) before May 15 planting can lead to 5-8 bushels per acre increase in soybean yield, while still reaching maturity by late-September. This system would provide greater soybean yields while allowing adequate time for an optimum wheat planting date after soybean harvest. However, for later soybean plantings (after mid-May), early-maturity varieties can be used without a soybean yield penalty while allowing adequate time for wheat planting.

Impact of planting date and maturity group selection
Figure 1. Impact of planting date and maturity group selection on soybean seed yield (bu/acre, left panel) and date to reach R7 stage (one mature pod on the main stem, right panel). Add 15-20 days to R7 to estimate harvest date. Data is average of four Michigan site-years.

Seeding depth

Attaining a consistent seed depth is important in order to increase the probability of even emergence. Usually, a planting depth of 1 to 1.5 inches is enough in heavy soil. Deeper seed placement may have an advantage when some types of winter stresses occur, but usually this is outweighed by the advantage in more rapid emergence posed by more shallowly placed seed. The exception may be where a coarse soil is very dry. In this case, seed should be planted as deep as possible to reach moist soil.

Seeding rate

The recommendation is to plant between 1.2 and 2.2 million seeds per acre. Seeding rates on the lower end of the range should be used when planting within a week of the fly-free-date to avoid overly thick stands that can promote disease development and increase the likelihood of lodging the following season. As the calendar advances, seeding rates should become progressively higher. If planting continues into the second half of October, the seeding rate should be increased to at least 1.8 million seeds per acre.

Table 2 identifies the pounds of seed needed based on the number of seeds per pound and your population target. For example, if seed size is 12,000 seeds per pound and the target seeding rate is 1.4 million seeds per acre, then 117 pounds of seed would be needed per acre. Table 3 is useful for assessing the number of seeds being dropped by each row unit (7.5-inch row spacing) and for evaluating actual seedling density. So, with the 1.4 million target, a 7.5-inch drill would drop approximately 20 seeds per foot and, assuming a 92% emergence rate, lead to an estimated 18.5 wheat seedlings.

Table 2. Relating seed size and target seeding rates to the number of pounds required per acre

Seed size (seeds per pound)

Target seeding rates (millions of seeds per acre)

1.2

1.4

1.6

1.8

2.0

2.2

Actual pounds of seed required per acre *

9,000

133

156

178

200

222

244

10,000

120

140

160

180

200

220

11,000

109

127

145

164

182

200

12000

100

117

133

150

167

183

13,000

92

108

123

138

154

169

14,000

86

100

114

129

143

157

15,000

80

93

107

120

133

147

16,000

75

88

100

113

125

138

*Target seeding rate divided by seeds per pound = required pounds of seed per acre.

 

Table 3. Relating target seeding rate per acre to seed and seedling numbers (for 7.5-inch row spacing)

 

Seeding rate (millions/ac)

Seeds per foot of row

Seedlings* per foot of row

 

1.2

17.2

16.2 (94%)

 

1.4

20.1

18.5 (92%)

 

1.6

23.0

20.7 (90%)

 

1.8

25.8

22.7 (88%)

 

2.0

28.7

24.7 (86%)

 

2.2

31.6

26.5 (84%)

 

*Projected number of seedlings based on an estimated declining emergence rate as percent.

  

Did you find this article useful?